//
// Simple passthrough vertex shader
//
attribute vec3 in_Position;                  // (x,y,z)
//attribute vec3 in_Normal;                  // (x,y,z)     unused in this shader.
attribute vec4 in_Colour;                    // (r,g,b,a)
attribute vec2 in_TextureCoord;              // (u,v)

varying vec2 v_vTexcoord;
varying vec4 v_vColour;

void main()
{
    vec4 object_space_pos = vec4( in_Position.x, in_Position.y, in_Position.z, 1.0);
    gl_Position = gm_Matrices[MATRIX_WORLD_VIEW_PROJECTION] * object_space_pos;
    
    v_vColour = in_Colour;
    v_vTexcoord = in_TextureCoord;
}

//######################_==_YOYO_SHADER_MARKER_==_######################@~
#pragma use(sampler)


	uniform int  interpolation;
	uniform vec2 sampleDimension;
	uniform int  sampleMode;

	const float PI = 3.14159265358979323846;
	float sinc ( float x ) { return x == 0.? 1. : sin(x * PI) / (x * PI); }

	vec4 texture2D_bicubic( sampler2D texture, vec2 uv ) {
		uv = uv * sampleDimension + 0.5;
		vec2 iuv = floor( uv );
		vec2 fuv = fract( uv );
		uv = iuv + fuv * fuv * (3.0 - 2.0 * fuv);
		uv = (uv - 0.5) / sampleDimension;
		return texture2D( texture, uv );
	}

	const int RSIN_RADIUS = 1;
	vec4 texture2D_rsin( sampler2D texture, vec2 uv ) {
		vec2 tx = 1.0 / sampleDimension;
		vec2 p  = uv * sampleDimension;
		
		vec4  col = vec4(0.);
		float wei = 0.;
		
		for (int x = -RSIN_RADIUS; x <= RSIN_RADIUS; x++)
		for (int y = -RSIN_RADIUS; y <= RSIN_RADIUS; y++) {
			vec2 sx = vec2(float(x), float(y));
			float a = length(sx) / float(RSIN_RADIUS);
			// if(a > 1.) continue;
			
			vec4 sample = texture2D(texture, uv + sx * tx);
			float w     = sinc(a * PI * tx.x) * sinc(a * PI * tx.y);
			
			col += w * sample;
			wei += w;
		}
		
		col /= wei;
		return col;
	}

	const int LANCZOS_RADIUS = 3;
	float lanczosWeight(float d, float n) { return d == 0.0 ? 1.0 : (d * d < n * n ? sinc(d) * sinc(d / n) : 0.0); }

	vec4 texture2D_lanczos3( sampler2D texture, vec2 uv ) {
		vec2 center = uv - (mod(uv * sampleDimension, 1.0) - 0.5) / sampleDimension;
		vec2 offset = (uv - center) * sampleDimension;
		vec2 tx = 1. / sampleDimension;
		
		vec4  col = vec4(0.);
		float wei = 0.;
		
		for(int x = -LANCZOS_RADIUS; x < LANCZOS_RADIUS; x++)
		for(int y = -LANCZOS_RADIUS; y < LANCZOS_RADIUS; y++) {
			
			float wx = lanczosWeight(float(x) - offset.x, float(LANCZOS_RADIUS));
			float wy = lanczosWeight(float(y) - offset.y, float(LANCZOS_RADIUS));
			float w  = wx * wy;
			
			col += w * texture2D(texture, center + vec2(x, y) * tx);
			wei += w;
		}
		
		col /= wei;
		return col;
	}

	vec4 texture2Dintp( sampler2D texture, vec2 uv ) {
			 if(interpolation <= 2)	return texture2D(          texture, uv );
		else if(interpolation == 3)	return texture2D_bicubic(  texture, uv );
		else if(interpolation == 4)	return texture2D_lanczos3( texture, uv );
		
		return texture2D( texture, uv );
	}

	vec4 sampleTexture( sampler2D texture, vec2 pos) {
		if(pos.x >= 0. && pos.y >= 0. && pos.x <= 1. && pos.y <= 1.)
			return texture2Dintp(texture, pos);
		
			 if(sampleMode <= 1) return vec4(0.);
		else if(sampleMode == 2) return texture2Dintp(texture, clamp(pos, 0., 1.));
		else if(sampleMode == 3) return texture2Dintp(texture, fract(pos));
		else if(sampleMode == 4) return vec4(vec3(0.), 1.);
		
		return vec4(0.);
	}


varying vec2 v_vTexcoord;
varying vec4 v_vColour;

uniform vec2 t1;
uniform vec2 t2;
uniform vec2 t3;
uniform vec2 t4;

mat3 m_inverse(mat3 m) {
    float a00 = m[0][0], a01 = m[0][1], a02 = m[0][2];
    float a10 = m[1][0], a11 = m[1][1], a12 = m[1][2];
    float a20 = m[2][0], a21 = m[2][1], a22 = m[2][2];

    float b01 =  a22 * a11 - a12 * a21;
    float b11 = -a22 * a10 + a12 * a20;
    float b21 =  a21 * a10 - a11 * a20;

    float det = a00 * b01 + a01 * b11 + a02 * b21;

    return mat3(b01, (-a22 * a01 + a02 * a21), ( a12 * a01 - a02 * a11),
                b11, ( a22 * a00 - a02 * a20), (-a12 * a00 + a02 * a10),
                b21, (-a21 * a00 + a01 * a20), ( a11 * a00 - a01 * a10)) / det;
}

mat3 computeHomography() {
    float x0 = 0., y0 = 0.;
    float x1 = 1., y1 = 0.;
    float x2 = 0., y2 = 1.;
    float x3 = 1., y3 = 1.;

    float u0 = t1.x, v0 = t1.y;
    float u1 = t2.x, v1 = t2.y;
    float u2 = t3.x, v2 = t3.y;
    float u3 = t4.x, v3 = t4.y;

    mat3 A = mat3(
        x0, y0, 1.0,
        x1, y1, 1.0,
        x2, y2, 1.0
    );

    vec3 b1 = vec3(u0, u1, u2);
    vec3 b2 = vec3(v0, v1, v2);

    vec3 h1 = m_inverse(A) * b1;
    vec3 h2 = m_inverse(A) * b2;

    mat3 H = mat3(
        h1.x, h1.y, h1.z,
        h2.x, h2.y, h2.z,
        0.0,  0.0,  1.0
    );

    return H;
}

void main() {
    mat3 H = computeHomography();

    vec3 warpedCoord = H * vec3(v_vTexcoord, 1.0);
    vec2 finalCoord  = warpedCoord.xy / warpedCoord.z;

    gl_FragColor = texture2D(gm_BaseTexture, finalCoord);
}